CHAPTER 31: Detection Methods to Monitor the Degradation of Organic Chloramines

Organic chloramines have been found to form in drinking water systems and they have been reported to potentially cause cytotoxic and genotoxic effects even at micromolar concentration levels. However, little information on the occurrence and toxicity of organic chloramines in drinking water is currently available. In this study, a triiodide colorimetric method, which was a modified standard iodometric method for colorimetric measurement, was used to determine the formation of organic chloramines that were not suitable for direct UV detection due to interference peaks in the 250 to 280 nm range. The triiodide colorimetric and direct UV methods were successfully applied to determine the rate of degradation of N-chloroglycine, N-chloroserine, N-chloroasparagine and N-chlorophenylalanine. The stability of these organic chloramines was found to vary, with their half-life ranging from 15 to 5775 min. The stability of the organic chloramines appeared to increase with increasing basicity of the amine nitrogen. The half-life values found for some of the organic chloramines investigated in this study suggest that their presence and persistence may be relevant in drinking water systems. In order to better characterise the risk associated with the occurrence of organic chloramines in drinking water, the stabilities of a wider range of organic chloramines should be investigated.